Polyurethane foams

ABSTRACT

Flame-resistant polyurethane foams are obtained by a process in which a tolylene diisocyanate (T.D.I.) is reacted with a polymeric polyol in the presence of a substance which is normally effective for the polymerisation of T.D.I. and an anti-ageing additive such as a halogenated aliphatic phosphate, of which the following is a specification.

This is a continuation of application Ser. No. 148,171, filed May 28,1971, now U.S. Pat. No. 3,803,064 granted Apr. 9, 1974.

This invention relates to flexible polyurethane foams, particularly toflame-resistant polyurethane foams, and to methods of making them.

Conventional polyurethane foams, particularly those derived frompolyethers, have little inherent resistance to burning(flame-resistance), and in view of the widespread use of polyurethanefoams in mattresses, cushions and other upholstery there exists a demandfor flame-resistant products. Previous proposals for reducing theinflammability of flexible polyurethane foams have included theincorporation in the foam-forming reaction mixture of certainconventional flame retardants, for instance halogenated alkylphosphates. However, these materials have either tended to be lost byevaporation during the foam-forming reaction or, if of sufficientmolecular weight to preclude substantial loss by evaporation they have,because of their relatively high density, tended to concentrate in thelower regions of foam products during manufacture, especially wheremanufacture is by a continuous, free-rise method producing a foam loaf.Consequently, in order to ensure that sufficient flame retardant isincluded in the upper regions of the loaf it has been necessary toincorporate in the foam-forming reaction mixture an amount of suchconventional flame retardant substantially in excess of that which wouldbe required if the retardant could be distributed evenly throughout thefoam loaf.

We have now found, according to the present invention, that flexibleflame-resistant polyurethane foams can be obtained by a process in whicha polymeric polyol is reacted with a tolylene diisocyanate (T.D.I.) in afoam-forming reaction mixture which contains: (a) as a foam modifier asubstance normally effective as a catalyst for the polymerisation oftolylene diisocyanate, and (b) an anti-ageing additive substantially tolimit any deleterious effect of the foam modifier on ageing of thepolyurethane foam.

By "polymerisation of tolylene diisocyanate" above is meant inparticular the polymerisation of three molecules of T.D.I. to produce acyclic trimer usually of isocyanurate or perhydrotriazine structure. Itis not known for certain whether the foam modifier in the presentinvention does in fact result in the polymerisation of the T.D.I. in thereaction mixture, but it is believed that polymerisation does occur, atleast where pure T.D.I. is initially present.

A particular advantage of the foams of this invention is that whensubjected to flame they give off much less smoke than do conventionalflame-resistant foams. This is a most valuable practical advantagebecause emission of noxious smoke and fumes when subjected to flame isone of the principal shortcomings of such conventional flame-resistantfoams.

Substances suitable as catalysts for the polymerisation of T.D.I., inparticular polymerisation to give trimers of isocyanurate structure, areshown in the literature such as Saunders, J. R. and Frisch K. C."Polyurethanes, Chemistry and Technology", Part 1, pages 94-97, & 212,Beitchmann, B. D. Rubber Age, Feb. 1966, Beitchmann B.D.I. & EC ProductResearch and Development, Vol.. 5, No. 1, pages 35-41, Mar. 1966, andNicholas, L. and Gmitter, G.T.J. Cellular Plastics, Vol. 1, No. 1, pages85-95 (1965).

Suitable substances are as follows:

a. Organic bases and salts and derivatives thereof, such as tertiaryamines. Examples are triethylamine, tetramethylguanidine, nickelderivatives of bipyridyl and N-alkyl morpholines.

b. Alkaline inorganic compounds such as hydroxides, carbonates, oxides,bicarbonates and peroxides, and basic salts of weak inorganic acids.Examples are sodium hydroxide, sodium carbonate, sodium bicarbonate,sodium sesquicarbonate, sodium peroxide, sodium tetraborate (borax),sodium stannate, sodium tungstate, sodium molybdate and sodium silicate.

c. Alkali metal and other basic salts and derivatives of organic acids,phenols, mono- or di- carboxylic acids of aliphatic or aromatic nature,and of other organic acids such as benzene sulphinic acid, nitrophenols, picric acid, phthalimide, diethyl phosphite, acetic acid,halogenated-acetic acids, phenol (C₆ H₅.OH) and other hydroxy-aromaticcompounds, and alcohols. The carboxylic acid salts can be of acidshaving 6-20 carbon atoms, for example salts of octoic, 2-ethyl hexoic,benzoic or oleic acids. Examples are sodium acetate, sodium formate,sodium phenate, sodium salts of monochloro- dichloro- and trichloro-acetic acids, sodium methoxide, lead heptane carboxylate (lead octoate),calcium naphthenate and sodium benzoate.

The potassium and lithium compounds corresponding to the sodiumcompounds referred to above under headings (b) and (c) can be used. Thecorresponding alkaline earth compounds can also be used, though theirefficacy is somewhat affected by their limited solubility.

d. Onium compounds of nitrogen, phosphorus, antimony, sulphur andselenium. Examples are tetramethyl-and tetraethyl- ammonium hydroxides,benzyltriethylammonium hydroxide, benzyltrimethylammonium hydroxide andtetraethyl phosphonium hydroxide. Of course, the particular substance orsubstances used as foam modifier in the process of the present inventionshould be such that there is no undesirable effect on the foam-formingreaction.

The foam modifiers of particular interest in the process of the presentinvention are basic substances, preferably readily soluble in water, andit is to such foam modifiers that the following description particularlyrelates.

The amount of the foam modifier incorporated depends upon the particularmodifier used and the nature of the components of the foam-formingreaction mixute. Although larger amounts can be used, it is not, ingeneral, necessary to use an amount greater than 1% by weight of thepolyol component, and the preferred amount is 0.05-1%, especially0.2-0.5%. However, where the foam modifier is a tertiary amine thepreferred amount is somewhat greater, and amounts of up to 5% or evenmore may be found necessary for good results. The foam modifier, wherewater-soluble, is conveniently incorporated as a solution in water, forexample in the water component of the foam-forming reaction mixture.

The polyol used in the production of the flame-resistant foams of thisinvention is normally a polyether polyol having a high reactivity,though polyesters can be used. Suitable polyether polyols are thosehaving a substantial proportion of primary hydroxyl end groups, usuallyreferred to as "ethylene oxide-tipped polyols". However, other polyolscan be used, and good results have been obtained using triols("non-tipped polyols") such as those sold under the Trade Mark VaranolCP.3720. Suitable ethylene oxide-tipped polyols are those in which theprimary hydroxyl groups comprise 20, 30, or 40% to 70% (for example50-60%) of the total number of hydroxyl groups in that polyol. Where thepolyol is a triol a suitable molecular weight is in the range 3000-6000.

A suitable polymeric polyol is one obtained by reacting a substancehaving a plurality of active hydrogen atoms with an alkylene oxide (forinstance propylene oxide or a mixture of propylene oxide and ethyleneoxide), and subsequently reacting the product thus obtained withethylene oxide so as to introduce the terminal primary hydroxyl groups.Polyether polyols of this type are commercially available under thetrade name Desmophen 3900 (which is a polyether triol of very highactivity having a mean molecular weight of 4500-5100 and a hydroxylnumber of 33-37), and Propylan M.12 described below with reference tothe Examples.

The flame retardant foams of the invention can be, for example, foams ofdensity up to 64 kg/m³, especially having densities in the range 16-64kg/m³.

There is a marked tendency for the foams of this invention to shrinkafter being made due to closed cells in the foam. This can be overcomeby mechanically squeezing or crushing the foam as is well known to thoseskilled in the art. However, we have found that shrinkage of theflame-resistant foams of the invention can be substantially obviated bythe use of a polyether polyol derived from ethylene oxide in which atleast some of the oxyethylene groups in the polyol molecule are innon-terminal positions. These subsidiary polyols which can for examplebe diols or triols, can contain from 20-80% (especially 40-70%) byweight of oxyethylene groups. Examples of suitable subsidiary polyolsare the commercial products and Propylan G.3650 of Lankro ChemicalsLimited. The subsidiary polyol can be used in any suitable porportionwith the major polyol, but we have found it to be effective insubstantially obviating the formation of closed cells if it is used inan amount of from 2-20 (for example 4-15) parts of the total polyolcomponent of the foam-forming reaction mixture. Care should be taken inthe amount of the subsidiary polyol used because too much leads tocollapse of the foam. The subsidiary polyol is conveniently apoly(oxyethylene) poly(oxypropylene) polyol whose poly(oxypropylene)content has a molecular weight in the range 500-2000, for instance800-1500. It can, for example, be a triol of molecular weight in therange 2000-3500. Where it has primary hydroxyl terminal groups they cancomprise, for example, 35-45% of the terminal groups. The subsidiarypolyol can be a substance consisting substantially of oxyethylenegroups. Polyethylene glycols of low molecular weight, for example in therange 300-800 have been found suitable.

The subsidiary polyvol is preferably fed to the mixer for thefoam-forming reaction mixture as a separate stream, though satisfactoryresults have been obtained where it has been previously blended with themajor polyol and the blend fed to the mixer.

It has further been found according to the present invention that theageing properties of the polyurethane foams can be improved, especiallywhere the foam modifier is a substance containing an alkali metal, forinstance sodium or potassium salts of phenols, or inorganic orcarboxylic acids, or alkali metal hydroxides, or other basic substance,if there is incorporated in the polyurethane foam-forming reaction aneutralising anti-ageing additive, for instance a labilehalogen-containing substance.

Suitable anti-ageing additives are as follows:

a. Halogen derivatives of phosphorus acids such as phosphoric,phosphorous and phosphonic acids.

Thus, the additives can be aliphatic phosphate esters, such as chloro-and bromo- derivatives of trialkyl orthophosphates, for examplecompounds of the formula R₃ PO where R is a halogenated -- preferablypolyhalogenated -- alkyl group of 2, 3 or 4 carbon atoms. Examples ofsuitable anti-ageing additives are (a) Halogen derivatives of phosphorusacids such as ortho-phosphoric acid, phosphorous acid. Examples are trisbromopropyl phosphate, tris chloropropyl phosphate, tris bromoethylphosphate, tris chloroethyl phosphate, tris 2,3-dibromopropyl phosphate,(T.B.P.P. -- which is particularly effective), tris 2,3-dichloropropylphosphate.

Other examples are: haloalkyl-alkenyl phosphates e.g.diallyl-2,3-dibromopropyl phosphate, bis (2,3-dibromopropyl) allylphosphate and bis (2,3-dichloropropyl) allyl phosphate; 2-bromodiglycolyl phosphate; haloalkyl phosphonates e.g. bis (2-bromoethyl)phosphonate; diallyl phenyl phosphonate; alkyl phosphonium chloridese.g. tetrakis (hydroxymethyl) phosphonium chloride; haloalkyl phosphitese.g. tris chloroethyl phosphite and tris bromoethyl phosphite.

b. Halogen derivatives of aliphatic (acyclic or alicyclic) or aromatichydrocarbons

Examples are derivatives of paraffins such as propane, e.g.1,2,3-tribromopropane; halogenated benzenes and substituted benzenes,e.g. chloro-benzenes and pentabromotoluene; chlorinated and brominatedpolyphenyls, e.g. biphenyl, diaminoethoxy polyhalogenated biphenyl,dihydroxy hexachloro biphenyl and dihydroxy octachloro biphenyl;halogenated cycloalkanes e.g. perchloropenta-cyclodecane and-cyclododecane, derivatives of cyclopentadiene and adducts thereof suchas adducts of hexachloro- or hexabromo- cyclopentadiene.

c. Halogen derivatives of aliphatic and aromatic hydroxy compounds asfollows:

Examples are derivatives of

Alcohols, Examples are dichloro-pentaerythritol, pentaerythritoldichlorohydrin, chloromethyl pentaerythritol,pentahalophenoxy-2,3-propane diol, e.g., dibromo neopentyl glycol and2(pentachlorophenoxymethyl)2-ethyl-1,3-propane diol,

Bisphenols, Examples are halogenated bisphenol A (2,2-diphenyl propane),e.g. 2,2-bis(4-hydroxy-3,5 dibromophenyl) propane, tetrachloro bisphenolA, epoxylated polyhalobisphenols,

Hydroquinones e.g. epoxylated tetrachlorohydroquinone.

d. Halogen derivatives of silicon compounds e.g. tetra(pentabromophenoxy) silane.

e. Halogen derivatives of ethers. Examples are: pentabromophenyl allylether, tribromophenyl allyl ether, halomethylated diaryl oxides and 1,2bis (2,6-dichloro-4-alkoxycarbonyl-phenoxy)ethane.

f. Halogen derivatives of resins

Examples are: chlorinated polyethylene, chlorinated p.v.c. andchlorinated paraffin wax.

g. Halogen derivatives of alkylene oxides e.g. trichloropropylene oxide.

Although many of the compounds referred to above are themselves flameretardants and they contribute towards the flame-resistance of thefoams, their effect in this direction is only minor and theflame-resistance of the foams is due in the main to the use of the foammodifier. The amount of anti-ageing additive to be used depends ofcourse upon the particular inhibitor and also the type of foam in whichit is to be used. However, in general an amount of 0.5-4 parts(especially 1.5-3 parts) per hundred parts of the polyol component hasbeen found to be effective. Such amounts are much less than the amountsin which, for example T.B.P.P. is conventionally used as a flameretardant additive -- usually about 15-20 parts per hundred of polyol.Where an organic bromo compound is used as the additive, it has beenfound that effective amounts are those corresponding to an amount of upto 0.25% (for example 0.05-0.1%) by weight of bromine per 100 parts ofpolyol component. Where the additive is a chloro compound the effectiveamounts are those corresponding to an amount of up to 0.5% (for example0.1-0.2%) by weight per 100 parts of polyol component.

The anti-ageing additives are in general covalent organic compoundswhich contain labile halogen atom or atoms. Such compounds can losetheir labile halogen (for example, as a result of interaction betweenthe halogen and alkali metal ions). The additives should be such thatneither they, nor the residual substance left after loss of the labilehalogen, have an undesirable effect on the reactions in the foam-formingreaction mixture. It is thought that the preferred additives, referredto above, probably do not lose their halogen until the early stages ofthe foam-forming reaction are complete, but that they then lose theirhalogen (perhaps due to the exothermic heat produced in the reaction)which can then combine with alkali metal ions in the reaction mixtureand thereby preclude their interference with the reaction mechanism ordeleterious effect on the foam product.

Small amounts of amine catalysts may be used in the process of theinvention, though it has not been found essential to use them where thepolyol is an ethylene oxide-tipped polyol; but they are more necessarywhen using non-tipped polyols. Examples of tertiary amines which can beused are, for example, dimethyl ethanolamine, N-methyl and N-ethylmorpholines, triethylamine, and triethylene diamine (also known as1,4-diazobicyclo 2,2,2,- octane).

Under certain circumstances, for example when harder foams are required,cross-linking agents may be employed. Examples of suitable cross-linkingagents are hydroxy amines, for example triethanolamine and tetrakis Nbeta-hydroxypropyl ethylene diamine (sold under the trade name Quadrol);low molecular weight polyols, such as tetrols, hydroxyethers, forexample tris-hydroxypropyl glycerol, and ortho-dichloro methylenebis-aniline.

In general the polyisocyanate and polyol components can be used inamounts such that the isocyanate index is of a normal value, for examplein the range 100-110. However, isocyanate index values outside thatrange can be used if desired, but it has not been found necessary toexceed a value of 150.

The T.D.I. can be in a substantially pure state. Where T.D.I. isreferred to herein it can contain one or more isomers thereof. Forexample, it can be tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate,or a mixture thereof, for instance in the proportions 65:35 (65:35T.D.I.) or, preferably, 80:20 T.D.I.) by weight.

The T.D.I. can be, for example, crude T.D.I. or T.D.I. in polymericform.

Crude T.D.I. is the product obtained by reacting the appropriatediamino-toluene with phosgene without any substantial pruification. Itis believed to contain material of polyurea and polybiuret structure.Where a mixture of 2,4- and 2,6-diamino-toluene is used, the crudeT.D.I. contain the corresponding 2,4- and 2,6-diisocyanates.

Polymeric T.D.I. is normally of uretdione or isocyanurate structure. Itcan be obtained from pure T.D.I. in a separate preliminary reactionusing polymerisation techniques well-known in the art and usingcatalysts referred to herein.

It has been found that the use in the process of the invention of largequantities of polysiloxane-oxyalkylene block copolymers should beavoided as they can detract from the flame-resistant properties of thepolyurethane foams obtained. If a polysiloxane-oxyalkylene blockcopolymer is used it should preferably be in an amount less than 0.1%and preferably not more than 0.05%. However, small proportions of apolydimethyl siloxane as used in the Examples below is notobjectionable, for example up to 0.1% by weight of the weight of thepolyol component. Even larger quantities can be used if desired, andsatisfactory foams have been obtained using amounts as follows:Viscosityof silicone Amount (parts per 100 ofpolyol)______________________________________2 centistokes 0.5-45 "0.025-0.2510 " 0.05-0.1______________________________________

The polyurethane foams of the invention can be obtained in moulded formby a cold-cure moulding method, that is, a method in which thefoam-forming reaction mixture is moulded and allowed to cure without theapplication of heat.

Moreover, the foams of the invention are suitable for use in flamelamination to textile and other substrates.

Although it is not intended that the present invention should beconstrued with reference to any particular theory, it is thought thatthe foam modifier has the effect of producing a polyurethane foam havinga structure different from that obtained in the absence of the foammodifier such that when subjected to flame the foam tends to collapseand thereby presents a reduced surface area to the flame. This view issupported by observation of what happens to a foam of the invention whensubjected to a flame. For example, when a lighted match is placed on ablock of the foam the portion subjected to the heat of the flame readilymelts or decomposes and "retracts" away from the flame but without anysustained burning.

The invention is illustrated by the following Examples, in whichflexible flame-resistant polyurethane foams are obtained by the one-shotor single stage method.

The meanings of various Trade Names used in the Examples are as follows:Propylan M.12 is the Trade Name of a polyether polyol sold by LankroChemicals Limited, and which is believed to be a poly(oxypropylene)poly(oxyethylene) triol having the following characteristics:

    Molecular Weight   about 5000                                                 Hydroxyl No.       35-37                                                      Poly(oxyethylene) content                                                                        about 12-13% by weight                                 

It has a high proportion of primary hydroxyl end groups.

G.978 is an abbreviation for "Development Polyol G978" sold by LankroChemicals Limited. It is used in the Examples as an anti-shrinkageagent, and is believed to consist essentially of a poly(oxyethylene)poly(oxypropylene) triol based on a glycerol "starter" and having amolecular weight of about 2800, a hydroxyl number of 53-59 and apoly(oxyethylene) content of about 64% by weight. The proportion ofprimary hydroxyl groups: secondary hydroxyl groups in this polyol isbelieved to be in the ratio 40:60.

It will be seen that in Example 3 the polyol component contained a thirdpolyol (as a cross-linking agent) referred to as "Quadrol" which isbelieved to consist essentially of the compound:

    (CH.sub.3 CH(OH)CH.sub.2).sub.2 N--CH.sub.2 --CH.sub.2 --N(CH.sub.2 --CH(OH)--CH.sub.3).sub.2

in the Examples the silicone MS.200/5 is a commercial silicone oilhaving a viscosity of 5 centistokes and believed to be a dimethylsiloxane homopolymer, and the tris-dibromopropyl phosphate (T.B.P.P.)anti-ageing additive was used in the form of the commercial productBromkal P.67. The T.D.I., except where states otherwise, was 80:20T.D.I. The hardness values were obtained under the test of BS.3667.Reference in the Examples simply to "catalyst" is to the foam modifier.

EXAMPLE 1

A flexible, free-rise polyurethane foam was obtained using the followingformulation:

    Propylan M.12                 90                                                              Polyol Component                                              G.978                         10                                              Water                         3                                               Sodium phenate                0.4                                             T.B.P.P.                      2                                               Silicone MS.200/5             0.05                                            T.D.I.                        36.5                                        

In this Example, and in the other Examples, the amounts of theingredients are shown in parts by weight.

The procedure used to make the foam was as follows.

First, the silicone was dispersed in 2.5 parts of the Propylan M.12polyol so as to provide a 2% solution; and the sodium phenate wasdissolved in all of the water component. The remainder of the polyolcomponent was then mixed with the T.B.P.P. and the polyol dispersion ofthe silicone by high speed stirring for 20 seconds. The aqueous solutionof the sodium phenate was then added to the mixture and the whole wasstirred for a further 15 seconds. Then the T.D.I. was added and thestirring was continued for a further 8 seconds, at the end of which timethe resulting foam-forming reaction mixture started to "cream" and wasimmediately poured into an open mould.

The rise of the foam was completed in 90 seconds, and the foam wastack-free at the end of about 15 minutes after the pouring. At this timethe resulting polyurethane moulding was removed from the mould.

The foam had a density of 29.4 kg/m³ and a hardness of 6 kg. and did notshrink on cooling.

EXAMPLE 2

A flexible, free-rise polyurethane foam was obtained using the followingformulation and the procedure described in Example 1:

    Propylan M.12                 90                                                              Polyol Component                                              G.978                         10                                              Water                         4                                               Sodium phenate                0.3                                             Silicone MS.200/5             0.05                                            T.B.P.P.                      2                                               T.D.I.                        46.5                                        

The foam had a density of 24 kg/m³ and a hardness of 7-8 kg. and did notshrink on cooling.

EXAMPLE 3

A flexible, free-rise polyurethane foam was obtained using the followingformulation and the procedure described in Example 1:

    Propylan M.12                 82.5                                            G.978           Polyol Component                                                                            12.5                                            Quadrol                       5.0                                             T.B.P.P.                      2                                               Water                         4                                               Silicone MS.200/5             0.05                                            Sodium phenate                0.25                                            T.D.I.                        52.4                                        

The foam had a density of 25.0 kg/m³ and a hardness of 13-15 kg. and didnot shrink on cooling.

EXAMPLE 4

A flexible, polyurethane foam cushion was obtained by a cold-mouldingtechnique using the following formulation:

    Propylan M.12                 95                                                              Polyol Component                                              G.978                         5                                               Water                         3                                               Sodium phenate                0.5                                             Triethylamine                 0.4                                             Silicone MS.200/5             0.05                                            T.B.P.P.                      2                                               T.D.I.                        36                                          

The foam-forming reaction mixture, obtained using the procedure ofExample 1, the triethylamine being dissolved in the polyol, wasdispensed into a metal mould which had been pre-heated to 50°C. Aclose-fitting lid was clamped into place on the mould by toggle clampsand the mould left for 10 minutes without any application of heat. Themoulded product was then removed from the mould. It was found to have adensity of 48 kg/m³ and did not shrink on cooling.

EXAMPLE 5

A flexible, free-rise polyurethane foam was obtained using the followingformulation and the procedure described in Example 1:

    Propylan M.12                 95                                                              Polyol Component                                              G.978                         5                                               Water                         3                                               Sodium phenate                0.4                                             T.B.P.P.                      2                                               T.D.I.                        41.2                                            Silicone MS.200/5             0.05                                        

The foam had a density of 29 kg/m³ and a hardness of 10 kg. and did notshrink on cooling.

EXAMPLE 6

A flexible, free-rise polyurethane foam was obtained using the followingformulation and the procedure described in Example 1, the triethylaminebeing dissolved in the polyol:

    Propylan M.12 (Polyol Component)                                                                     100                                                    Water                  4.5                                                    Sodium phenate         0.25                                                   Triethanolamine        0.5                                                    Silicone MS.200/5      0.05                                                   T.B.P.P.               2                                                      T.D.I.                 51.3                                               

The foam thus obtained had a closed-cell structure but this was easilyconverted into an open-cell structure by passage through rollers. Therolled product had a density of 18.9 kg/m³ and a hardness of 8.5 kg.

The foams of the Examples were all found to have excellentflame-resistance. When tested under the conditions of ASTM D 1692 67Tthe following results were obtained:

            EXAMPLE                                                                       1     2         4       5       6                                     ______________________________________                                        Mean extent                                                                   burned (mm)                                                                             14      29        13    22      29                                  Burning time                                                                  (seconds) 10      22        13    24      12                                  Burning rate                                                                  (mm/second)                                                                             1.4     1.32      1.0   0.91    2.4                                 ______________________________________                                    

Besides their excellent flame-resistance, the foams of these Exampleswere found to have high resilience -- more than 50% as measured by thefalling ball rebound test -- and to show a relatively linearload-deflection relation.

EXAMPLES 7-14

Further flexible polyurethane foams were obtained using the procedure ofExample 1 and the following formulations.

    __________________________________________________________________________    Example No.                                                                           7    8    9    10   11     12   13        14                          __________________________________________________________________________    Catalyst                                                                              Sodium Hydroxide                                                                        Sodium Carbonate                                                                        Sodium Sodium                                                                             Benzyl trimethyl                                                                        Potassium                                     (anhydrous)                                                                             Stannate                                                                             Formate                                                                            ammonium phenoxide                                                                      Phenate                                                 (Na.sub.2 SnO.sub.3.)                                                         3H .sub.2 O)                                      __________________________________________________________________________    (parts) 0.15 0.25 0.4  0.2  0.5    0.4  0.5       0.45                        Propylan                                                                              90   90   90   90   90     92.5 90        90                          M.12                                                                          G.978   10   10   10   10   10     7.5  10        10                          Water   4.5  4.5  4.5  4.5  4.5    4.5  3         3                           T.B.P.P.                                                                              2    2    2    2    2      0.4  2         2                           Silicone                                                                      MS.200/5                                                                              0.05 0.05 0.05 0.05 0.05   0.05 0.05      0.05                        T.D.I.  54   54   54   54   54     36.2 36.2      36.2                        Propamine A                                                                           --   --   --   0.2  0.2                                               Foam                                                                          Density 21   21   21   31   31     30   30        30                          (kg./m..sup.3)                                                                __________________________________________________________________________

The foam of each of Examples 7-14 was found to be self extinguishingwhen tested according to ASTM D 1692/67T. That test was used for theproducts of all the following Examples except if stated otherwise.

Example 7 was repeated using the G.978 in amounts of 7.5, 8.5, 9, 11, 12and 13.5 parts, instead of the 10 parts used in that Example. In eachcase the amount of Propylan M.12 used was such that the total weight ofPropylan M.12 and G.978 was 100 parts. The foam products obtained ineach case were self-extinguishing.

EXAMPLES 15-18

Example 7 was repeated but using the following labile halogen compoundsinstead of the T.B.P.P. Example 15: tris 2,3-dichloropropyl phosphate(as the commercial product Fryol F.R.2 -- 2 parts) Example 16: trisβ-chlorethyl phosphate (4 Parts) Example 17: 1,2,3-tribromo propane (1.2parts) Example 18: dibromo-neopentyl glycol (2 parts) (In Example 18 theamount of T.D.I. was increased to 37.6 to take account of the hydroxylgroups in dibromo-neopentyl glycol).

The foam product of each of these Examples was self-extinguishing, anddid not suffer deterioration on heat ageing for 16 hours at 140°C.However, in comparative Examples in which the halogen compound wasomitted, the foam products had deteriorated so much at the end of 16hours heat ageing that their relevant physical properties could not bemeasured.

EXAMPLES 19-21

These Examples illustrate the use of anti-shrinkage agents other thanthe polyol G.978 to obviate shrinkage of flexible foam products.

The procedure and formulation of Example 7 was repeated except that thefollowing amounts of anti-shrinking agents were used instead of theG.978. In each case the total amount of Propylan M.12 and anti-shrinkageagent was 100 parts.

Example 19 Polyol R.161: 10-11.5 (for example 11.5) parts

Example 20 Polyol 1138: 9 (for example 7) parts

Example 21 Polyethylene glycol (PEG 600): 10-11.5 (for example 11) parts

Polyol R.161 and Polyol DP 1138 are respectively polyether triols soldby Union Carbide Corporation and Lankro Chemicals Limited. They havemolecular weights in the range 2500-3500 and poly(oxyethylene) contentsof about 65% and 79% by weight. The foam products obtained wereself-extinguishing.

EXAMPLE 22

This describes the production of a flexible polyurethane foam mouldingby the cold cure technique using a typical formulation of the presentinvention.

Propylan M.12 (288g.) was blended with 12g. of polyol G.978, 9 g. sodiumcarbonate solution (20g. Na₂ CO₃ in 280g. water), 0.9 g. Dabco 33LV,0.69 g. silicone MS.200/5 and 3.0 g. 98% pure triethanolamine. The blendwas mixed with a high speed stirrer for 10 seconds, 30 g.trichlorofluromethane was added and stirring continued for a further 10seconds. 114 g. of T.D.I. was then added and further stirred for 10seconds. The mixture was the poured into a mould having a surfacetemperature of 58°C. The mould lid was clamped into place and themoulding left to cure without the application of heat for 10 minutes.The moulding obtained was of good appearance its density was 37 kg/m³and the foam was self-extinguishing.

EXAMPLE 23

This Example illustrates the use of sodium salts of halogenated aceticacids as catalyst. Using the procedure of Example 1 flexible, free-risefoams were obtained from the following formulation.

    ______________________________________                                        Propylan M.12                85.5                                             G.978         Polyol Component                                                                             12.5                                             Polyol EDP.500           2                                                    Water                    4.5                                                  Sodium monochloro acetate (S.M.C.A.)                                                                   0.4                                                  Propamine A              0.4                                                  T.B.P.P.                 2                                                    Silicone MS.200/5        0.05                                                 T.D.I.                   63                                                   ______________________________________                                    

The foam density was 21.9 kg/m³ and the burned length was 22 mm.

The polyol EDP.500 is a low molecular weight cross-linking tetrol,believed to contain ethylene diamine as starter nucleus and having amolecular weight about 500.

EXAMPLES 24 and 25

Example 23 was repeated except that instead of the S.M.C.A. was usedrespectively 0.52 part sodium dichloroacetate and 0.64 part sodiumtrichloroacetate. The flexible foam products obtained were as follows:

Example 24 -- density 21.8 kg/m³ ; burned length 26 mm.

Example 25 -- density 21.9 kg/m³ ; burned length 22 mm.

EXAMPLE 26

Example 23 was repeated but using tetramethyl guanidine (0.3 part) ascatalyst instead of the S.M.C.A., and 0.3 part of Dabco 33 LV instead ofthe Propamine A. The flexible foam obtained was self-extinguishing.

EXAMPLE 27

Tetramethylammonium hydroxide was used as catalyst in the followingformulation to produce a flexible foam.

    ______________________________________                                        Propylan M.12      95                                                         G.978              5                                                          Water              4.5                                                        T.D.I.             61.5                                                       Silicone MS.200/5  0.05                                                       (CH.sub.3).sub.4 N. OH                                                                           0.34                                                       T.B.P.P.           1                                                          ______________________________________                                    

The foam obtained was self-extinguishing.

In a comparative Example withour T.B.P.P. the foam, thoughself-extinguishing, lost its flame resistant properties after heatageing at 140°C. for 41/2 hours.

EXAMPLES 28 and 29

These Examples illustrate the use as the major polyol of a poly(oxypropylene) poly(oxyethylene) triol sold by the Dow Chemical Companyunder the Trade Mark Voranol CP-3720. This polyol has a molecular weightof about 3500 and is believed to have a poly(oxyethylene) content,substantially in nonterminal positions, of about 10-11% by weight.

Flexible foams were obtained from the following formulations:

    Example 28         Example 29                                                 ______________________________________                                        Voranol CP-3720                                                                          100         Voranol CP-3720                                                                            100                                       Water      4.5         Water        4.5                                       T.B.P.P.   2           Na.sub.2 CO.sub.3                                                                          0.2                                       Daltogard WP                                                                             1           Silicone L-546                                                                             0.35                                      NaOH       0.15        Daboo 33 LV  0.40                                      Stannous octoate                                                                         0.10        T.D.I. (120                                            Silicone L-546                                                                           0.35        index)       60.5                                      T.D.I. (135 index)                                                                       68.30                                                              Density    25.8 kg/m.sup.3                                                    M.E.B.     87.5 mm.                                                           ______________________________________                                         Daltogard WP is triphenyl phosphite, and                                      Silicone L-546 is a polydimethyl siloxane poly(oxyalkylene) block             copolymer.                                                               

EXAMPLE 30

This Example illustrates the use of co-catalysts with the T.D.I.polymerisation-type catalyst. A flexible foam was obtained from thefollowing:

    Propylan M.12      92.5                                                       G.978              7.5                                                        T.D.I. (135 index) 66.5                                                       Water              4.5                                                        T.B.P.P.           2                                                          Daltogard WP       1                                                          NaOH               0.15                                                       Propamine A        0.2                                                        Silicone MS.200/5  0.05                                                   

The foam product was self-extinguishing, mean extent burned being 43 mm.

EXAMPLE 31

Example 30 was repeated but using 0.2 part of N,N-dimethylbenzylamine inplace of the Propamine A. The product was self-extinguishing, meanextent burned being 54 mm.

EXAMPLE 32

Isophorone diisocyanate (IDI) was used in conjunction with the T.D.I. toprovide a flexible foam.

    ______________________________________                                        Propylan M.12      90                                                         G.978              10                                                         T.D.I.             53.3                                                       Isophorone DI      15                                                         Water              4.5                                                        T.B.P.P.           1                                                          Na.sub.2 CO.sub.3  0.2                                                        Propamine A        0.2                                                        Silicone MS.200/5  0.05                                                       ______________________________________                                    

The product was self-extinguishing, mean extent burned being 39 mm.

EXAMPLE 33

A crude M.D.I. sold under the Trade Mark Isonate 143-L, and believed tobe a carbodiimide-modified M.D.I. was used in conjunction with T.D.I.

    Propylan M.12       95                                                        G.978               5                                                         T.D.I.              45.5                                                          NCO index 135                                                             M.D.I.              30                                                        Water               4.5                                                       T.B.P.P.            2                                                         Daltogard WP        1                                                         Na.sub.2 CO.sub.3   0.2                                                       Propamine A         0.2                                                       Silicone MS.200/5   0.05                                                  

The foam product was self-extinguishing, mean extend burned being 17 mm.

EXAMPLES 34-43

Ten further flexible foams were obtained using various catalysts in thefollowing formulations. Comparative foams using the same formulationsbut without T.B.P.P. and Daltogard WP were also produced.

On hot oven ageing at 140°C. it was found that the comparative foams hadsubstantially lost their flame-resistance after 5 hours, and after 16hours they had deteriorated so much that their relevant physicalproperties could not be measured. On the other hand, the foams of theinvention had retained their flame-resistance, and their physicalproperties were only little worse than before ageing. Indeed, theirtensile strength and elongation at break were better.

    __________________________________________________________________________    Example No.                                                                          34   35    36   37  38    39    40    41    42  43                                            Sodium                                                                            Sodium                                             Catalyst                                                                             Sodium                                                                             Sodium                                                                              Sodium                                                                             Bicarb-                                                                           sesqui-                                                                             Lithium                                                                             Potassium                                                                           Potassium                                                                           Sodium                            Tungstate                                                                          Molybdate                                                                           Acetate                                                                            onate                                                                             carbonate                                                                           Hydroxide                                                                           Acetate                                                                             Hydroxide                                                                           Silicate                                                                          Ni(O)(bipyridyl).su                                                           b.2                    __________________________________________________________________________    No. of                                                                        parts of                                                                             0.8  0.8   0.6  0.2 0.2   0.42  0.6   0.2   0.4 0.4                    catalyst                                                                      Propylan                                                                      M.12   90   90    90   90  90    90    90    90    90  95                     G.978  10   10    10   10  10    10    10    10    10  5                      Water  4.5  4.5   4.5  4.5 4.5   4.32  4.5   4.5   4.5 3                      T.B.P.P.                                                                             2    2     2    2   2     2     2     2     2   2                      Daltogard WP                                                                         1    1     1    1   1     1     1     1     1   1                      MS.200/5                                                                             0.05 0.05  0.05 0.05                                                                              0.05  0.05  0.05  0.05  0.05                                                                              0.05                   T.D.I. 61.5 61.5  61.5 66.5                                                                              66.5  61.5  61.5  61.5  61.5                                                                              43.4                   Mean                                                                          Extent                                                                        burned mm.                                                                           54.8 75    42.3 28.8                                                                              17.5  47.4  53.7  32.5  76.2                       (BS 4735)                                                                     __________________________________________________________________________     The sodium sesquicarbonate was used in the form of an aqueous solution        prepared by dissolving equimolar amounts of sodium carbonate and sodium       bicarbonate in water: this solution was used directly in the foam             formulation without isolating the sesquicarbonate.                            All the foam products had densities in the range 19-25 kg/m.sup.3.            In Example 43 there was used 0.6 part of N-ethyl morpholine.             

We claim:
 1. A flexible flame-retardant polyurethane foam prepared bythe process which comprises reacting a tolylene diisocyanate with apolyalkylene ether polyol having from 20 to 70% primary hydroxyl groupsin a foam forming reaction mixture having an isocyanate index of lessthan 150 and containing (a) a compound which promotes trimerization oftolylene diisocyanate, (b) an amount of a compound containing labilehalogen which inhibits heat aging of the foam caused by saidtrimerization promotor, and (c) a blowing agent, said polyalkylene etherpolyol having a reactivity such that said reaction mixture, in theabsence of special measures to the contrary, produces a closed cellfoam; and said reaction mixture contains an additional polyol which isdifferent in its constitution from said polyalkylene ether polyol andwhich is a polyethylene ether glycol or a poly(oxyethylene)poly(oxypropylene glycol) wherein the poly(oxypropylene) content has amolecular weight of 500 to 2000 and wherein from 20 to 80% of its weightis oxyethylene groups at least some of which are in non-terminalpositions, and said additional polyol is from 2 to 40% by weight of thetotal polyol.
 2. A product according to claim 1 in which the polyol is atriol and the primary hydroxyl groups comprise 40 to 70% of the totalnumber of hydroxyl groups.
 3. A product according to claim 1 in whichthe polyol is a poly(oxyethylene) poly(oxypropylene) triol having apoly(oxyethylene) content of up to 20% by weight.
 4. The product ofclaim 1 wherein the said mixture contains 0.5 to 4 parts of labilehalogen containing compound per 100 parts polyalkylene ether polyol. 5.The product of claim 1 wherein the labile halogen containing compound isa halogenated aliphatic phosphate ester.
 6. The product of claim 1wherein the polyol is a polyalkylene ether glycol or polyalkylene ethertriol.
 7. The product of claim 1, wherein the labile halogen containingcompound is a halogenated aliphatic phosphate ester.
 8. The product ofclaim 7, wherein the labile halogen containing compound is a chloro- orbromo-derivative of a trialkyl ortho-phosphate.
 9. The product of claim8, wherein the labile halogen containing compound is tris2,3-dibromopropyl orthophosphate.
 10. The product of claim 8, whereinthe labile halogen containing compound is tris bromopropyl phosphate,tris chloropropyl phosphate, tris bromoethyl phosphate, tris chloroethylphosphate or tris 2,3-dichloropropyl phosphate.
 11. The product of claim1, wherein the labile halogen containing compound is a halogenatedaliphatic hydrocarbon or a halogenated aromatic hydrocarbon.